Eliminate some compile warnings (#600)

* Remove some unused variables
* remove duplicate "using .." by sorting and deduping the list
* Remove things that already exist in the parent class (in one case I moved some documentation to the parent)
* EntityBodyData and and NextSearch were never set (only read), removed
* _timeout was never read, subsequently _timer became unused. part of a TODO timeout functionality that was not implemented yet

MediaBrowser.Controller/Entities/BaseItem.cs

@@ -357,7 +357,7 @@ namespace MediaBrowser.Controller.Entities
         {
             var list = new List<Tuple<StringBuilder, bool>>();
 
-            int thisMarker = 0, thisNumericChunk = 0;
+            int thisMarker = 0;
 
             while (thisMarker < s1.Length)
             {